1. Technical Field
The present invention relates to a pixel circuit having a driven element, such as an organic light-emitting diode element, which is driven by a current, a method of driving the pixel circuit, an electro-optical device, and an electronic apparatus.
2. Related Art
In recent years, as a next-generation light-emitting device and as an alternative to the liquid crystal elements, an organic light-emitting diode element (hereinafter, referred to as ‘an OLED element’) called an organic electroluminescent element or a light-emitting polymer element has been drawing considerable attention. The OLED elements have a low viewing angle dependency because they are self-emitting elements. Further, since backlight or reflected light is not required, the OLED elements have excellent characteristics such as low power consumption and a reduced thickness as a display panel.
The OLED elements are current driven elements in which the light-emitting state cannot be maintained when the current is blocked because they do not have the voltage maintenance like the liquid crystal elements. Thereby, in the case of driving the OLED elements in an active matrix manner, the structure has been generally used, in which the voltage according to the gray scale degree of a pixel is applied into the gate of a driving transistor to hold the voltage by the gate capacity or a capacitive element during a writing period (selection period) and the driving transistor makes the current according to the gate voltage to flow into the OLED element continuously.
However, in this structure, there is a problem in that the luminance of the OLED element is different for each pixel by the deviation in the characteristics of the driving transistor to deteriorate the quality of display. For this reason, despite the presence of the deviation in the characteristics of the driving transistor, various types of technologies for suppressing the deviation of the current flowing into the driven element have been suggested. For example, there is a technology in which the deviation is offset by forming a current mirror circuit with at least two sets (four or more) of transistor groups (Japanese Unexamined Patent Application Publication 10-197896 is an example of related art) or a technology in which the deviation is offset by periodically changing the corresponding relationship between the current supplying circuit and the current supply destination. Japanese Unexamined Patent Application Publication 2003-66903 is another example of related art.
However, in the technology disclosed in Japanese Unexamined Patent Application Publication 10-197896, because of the difference in the manufacturing processes, there is a possibility that the deviation in the current still remains. Particularly, a large display apparatus has a tendency for having a greater deviation, and thus it is difficult to overcome the nonuniformity in the display. Also, in the technology disclosed in Japanese Unexamined Patent Application Publication 2003-66903, since the deviation is asymmetrically distributed in each block of the current supplying destination, there is a problem in that the nonuniformed display having a block shape is often generated.